Space heater



B. VONK SPACE HEATER April 23, 1963 Filed 001;. 7, 1958 INVENTOR.BASTIAAN VONK ATTORNEY 5 United States Patent M 3,087,041 SPACE HEATERBastiaan Vonk, Oegstgeest, Netherlands, assignor to Era HeaterCorporation, Vaduz, Liechtenstein Filed Oct. 7, 1958, Ser. No. 765,756Claims priority, application Netherlands Oct. 9, 1957 5 Claims. (Cl.219-34) This invention relates to space heaters.

A disadvantage inherent in radiators having electrical filaments andsimilar electrical heating elements and also in gas stoves such as theso-called infra-red radiators, which, like electrical stoves, do notfunction with a clearly visible flame, is that they cannot be used inspaces in which there is any danger of explosions or fire.

Spaces in which there are or may "be inflammable or explosive liquids,vapours or gases include, for example, garages and workshops, lacquerspraying plants, various chemical plants, drying installations as wellas spaces in which powdery substances are stored and processed and inwhich there may be air-and-dust mixtures that could give rise toexplosions. On account of the danger of fire and explosion it isimpossible in such spaces to use an open fire, even in the form ofelectric filaments or incandescent ceramic surfaces.

The object of the present invention is to provide a heating apparatusthat can be used in such spaces without danger of fire or explosion.

According to the invention the glowing or incandescent element or theflame is isolated from the surrounding atmosphere by means of a layer ofloose quartz wool or wool made from glass having a very high meltingpoint, said layer being at some distance from the incandescent elementand/or the flame.

It is of course known that combustion may take place in a layer of finefibrous quartz wool in which a catalyst has been placed. In that casethe aim is to bring the quartz wool to the state of incandescence. Inaccordance with the present invention, however, no combustion takesplace in the layer of quartz wool or glass wool, which consequently doesnot glow and which is arranged at some distance from the heating source.

The invention is based on some surprising observations. If a metal wireis placed at some distance from an electrical filament or an infra-redradiator at high temperature the metal wire wtll become incandescent.Obviously such an incandescent surface cannot come into contact with anexplosive atmosphere. This incandescence occurs both when heat isapplied without any flame, as is the case with electrical filaments, andwhen the heating element is a glowing ceramic mass provided with poresor channels, over which there may further be provided gas flames. If, onthe other hand, a thin film of quartz wool or glass wool is placed forinstance on the spirals of an electric heater, then it will not gloweven after a longer period. The heating source is, however, visiblethrough the glass film or through the quartz film, thus possibly givingthe impression that the film is glowing, which is actually not the case.As the film does not glow, it is possible for dangerously explosive airor even dangerously inflammable liquid to come into contact with saidfilm without any explosion occurring. Owing to the structure of a layerof glass wool or quartz wool a most surprising visual effect isobtained, thereby creating the impression of a completely incandescentsurface emitting infra-red rays. Since glass wool and quartz woolconsist of very fine threads having a thickness of the order of l-'l00microns and the apparent specific weight of such wool is very low, theinfra-red rays are capable of pene- 3,087,041 Patented Apr. 23, 1963trating virtually unhindered through a layer of such wool, whereby theheat efiiciency of the heating apparatus according to the invention isadversely affected only to a very minor extent. The threads themselvesare incombustible and fireproof and resist temperatures of SOD-900 C. ofthe customary infra-red radiators. Experiments have shown that heat rayshaving a wave length of about 4-2.5 microns pass practically unhinderedthrough a film of glass wool. Quartz wool and glass wool have low heatconductivity and in addition a low capacity for accumulating heat and ahigh specific heat, so that the material is particularly suitable forisolating the heating elements from the surrounding atmosphere. In thisrespect quartz wool is preferable to glass wool.

Whilst by arranging a plate of quartz wool or glass wool in front of theheating elements the latter are isolated from the surroundingatmosphere, care should of course be exercised that an explosive gasmixture is prevented from coming near the heating elements in any otherway than through the plane of radiation. This means that in practice theheating apparatus must 'be constructed in such a way that any access ofair from the atmosphere to the heating elements along any other paththan through the glass wool or quartz wool is rendered impossible.Therefore, an electrical ignition will preferably be provided, so thatin order to ignite the gas it is not necessary to open the space inwhich the heating elements are disposed behind the glass wool or quartzwool plate. With a gas apparatus the aforesaid screen by means of quartzwool or glass wool may be effected in such a way that this screen isefiective not only at the side of radiation, but also at the side wherean air-and-gas mixture is supplied, so that along this path also it isimpossible for an explosive mixture to come into contact with the sourceof heating.

It is noted that for preventing explosions in mines a so-called Davylamp is used, in which a fine mesh metal tissue is applied. Thisprinciple cannot be applied to heat radiators, since in that case toomany heat rays would be prevented from passing.

In order that the invention may be more clearly understood variousembodiments will now be described by way of example with reference tothe accompanying drawings in which:

FIGURE 1 is a diagrammatic cross-section illustrating the application ofthe invention to an electrical space heater,

FIGURE 2 is a similar view of a modified electrical space heater, and

FIGURES 3 and 4 are similar views illustrating the applications of theinvention to gas operated space heaters.

The heating apparatus according to FIGURE 1 comprises a number ofheating elements formed by an insulating core 1 made for instance fromporcelain or steatite around which electric filaments 2 are wound.Behind each filament is mounted a reflector 3, the unit as a whole beingencased in a housing 9. According to the invention the front side ofthis housing is closed oil by a plate of loose glass wool or quartz wool5. This plate is encased at its edges in a fire-proof frame 10, which isjoined to the housing of the electrical radiator. As glass wool haslittle rigidity, the front and rear side of the plate of wool arepreferably covered with a metal gauze or a gauze made from anotherincombustible material. This gauze may be of coarse mesh size and servesmerely to keep the glass wool in position. The glass wool plate can forinstance be mounted in such a way that its side closest to the filamentspirals rests against a gauze or grid 7 which is connected at 6 with thehousing 9 or with the frame 10. The gauze 3 or grid 8 may in that caserest on the other side of the wool plate and may be connected at thefront with the frame 10.

According to the embodiment shown in FIGURE 2 an electric filament 2 ismounted as a continuous spiral in a continuous channel 11 in aninsulating supporting member 4. The channel 11 may be shaped in azig-zag fashion or in the form of a spiral. The filament is in this casesituated rearwardly in respect of the surfaces 12 of the parts betweenthe channels. The plate of glass Wool or quartz Wool may in this wayrest directly on the surfaces 12 of the supporting member 4 without anystilfening grid or gauze. In this case also, the plate 5 is encased in aframe 10, whilst at the front is provided the grid or gauze 8 which isconnected with the frame 10.

In addition to electrically heated heating elements the invention canalso be applied to gas operated so-called infra-red radiators as inFIGURE 3. The plate of glass Wool or quartz wool 5 is also in this caseencased in a frame 10 and is provided with stiffening grids 7 and 8.Such a plate is mounted over a ceramic burner plate 13 which is providedwith the usual bores 14. This burner plate 13 is encased in a metalhousing 15 which is provided with an injector system 16. The plate 5together With the frame 10 is mounted gas-tight on the housing 15.

A similar heating apparatus is shown in FIGURE 4. In this case theglowing element 17 consists of a metal wire tissue or wickerwork fixedto a housing 18 into which a gas-and-air mixture is supplied through aninjector 19. Above the glowing element 17 a plate 5 of glass or quartzwool according to the invention is fixed to the supporting grids 7 and 8and a frame 10. A reflector 20 may be connected to the plate 5. Asalready stated above, an electrical ignition device is preferably usedWith the devices according to FIGURES 3 and 4, so that the interior ofthe apparatus need not be opened for igniting the gas flame.

Since the danger of fire and explosion is completely eliminated in theapparatus according to the invention, the filaments in electricalheating apparatus may be very heavily charged, namely with temperaturesexceeding 1000 C. The consumption of energy can thereby be reduced,whilst it is also possible to save material.

I claim:

1. A space heater comprising an incandescent source of heat; and anenclosure surrounding said source and completely separating it from theexternal atmosphere, at least one wall of said enclosure comprising alayer composed of a material selected from the group consisting of glasswool and quartz wool spaced apart from said source said wall beingsubstantially transparent to heat radiations from said source.

2. A space heater comprising an incandescent source of heat; and anenclosure surrounding said source and completely separating it from theexternal atmosphere, at least one wall of said enclosure comprising alayer composed of a material selected from the group consisting of glasswool and quartz wool spaced apart from said source, said Wall beingsubstantially transparent to heat radiations from said source, and ametal screen in contact with said material and attached to saidenclosure to hold said material in place.

3. A space heater comprising an incandescent source of heat; anenclosure partially surrounding said source, said enclosure having anopen side; and a cover fitting over said open side to cooperate withsaid enclosure to separate said source completely from atmosphereexternal to said enclosure, said cover being substantially transparentto heat radiations from said source and comprising a pair of wire gauzescreens, a layer composed of a material selected from the groupconsisting of glass wool and quartz wool between said screens, and aframe holding said screens and said material together.

4. A space heater comprising an incandescent electrical filament, aninsulating supporting member for said filament; an enclosure surroundingsaid filament and completely separating it from the external atmosphere,at least one wall of said enclosure comprising a layer composed of amaterial selected from the group consisting of glass Wool and quartzwool separated from said filament, said wall being substantiallytransparent to heat radiations from said filament, and a pair of wiregauze screens on either side of said material and in contact therewith,said screens being attached to said enclosure.

5. A space heater according to claim 4 comprising in addition areflector on the opposite side of said filament from said material andbetween said filament and said enclosure to reflect heat from saidfilament through said material.

References Cited in the file of this patent UNITED STATES PATENTS1,237,858 Ballenger Aug. 21, 1917 1,472,171 Haynsworth Oct. 30, 19232,349,300 Olsen May 23, 1944 2,641,313 Crossman June 9, 1953 FOREIGNPATENTS 505,043 Germany Aug. 12, 1930 206,122 Australia May 12, 19551,138,885 France Feb. 4, 1957

3. A SPACE HEATER COMPRISING AN INCANDESCENT SOURCE OF HEAT; ANENCLOSURE PARTIALLY SURROUNDING SAID SOURCE, SAID ENCLOSURE HAVING ANOPEN SIDE; AND A COVER FITTING OVER SAID OPEN SIDE TO COOPERATE WITHSAID ENCLOSURE TO SEPARATE SAID SOURCE COMPLETELY FROM ATMOSPHEREEXTERNAL TO SAID ENCLOSURE, SAID COVER BEING SUBSTANTIALLY TRANSPARENTTO HEAT RADIATIONS FROM SAID SOURCE AND COMPRISING A PAIR OF WIRE GAUZESCREENS, A LAYER COMPOSED OF A MATERIAL SELECTED FROM THE GROUPCONSISTING OF GLASS WOOL AND QUARTZ WOOL BETWEEN SAID SCREENS, AND AFRAME HOLDING SAID SCREENS AND SAID MATERIAL TOGETHER.